Conventional ultrasound scanners create two-dimensional B-mode images of tissue in which the brightness of a pixel is based on the intensity of the echo return. The basic signal processing chain in the conventional B mode is depicted in FIG. 1. An ultrasound transducer array 2 is activated to transmit an acoustic burst along a scan line. The return RF signals are detected by the transducer elements and then formed into a receive beam by the beamformer 4. The beamformer output data (I/Q or RF) for each scan line is passed through a B-mode processing chain 6 which includes demodulation, equalization filtering, envelope detection and logarithmic compression. Depending on the scan geometry, up to a few hundred vectors may be used to form a single acoustic image frame. To smooth the temporal transition from one acoustic frame to the next, some acoustic frame averaging 8 may be performed before scan conversion.
In general, the log-compressed display data is converted by the scan converter 10 into X-Y format for video display. On some systems, frame averaging may be performed on the X-Y data (indicated by dashed block 12) rather than the acoustic frames before scan conversion, and sometimes duplicate video frames may be inserted between acoustic frames in order to achieve a given video display frame rate. The scan-converted frames are passed to a video processor 14, which maps the video data to a gray-scale mapping for video display. The gray-scale image frames are then sent to a video monitor 18 for display.
System control is centered in a host computer 20, which accepts operator inputs through an operator interface 22 (e.g., a keyboard) and in turn controls the various subsystems. (In FIG. 1, only the image data transfer paths are depicted.) During B-mode imaging, a long sequence of the most recent images are stored and continuously updated automatically in a cine memory 16. Some systems are designed to save the R-.theta. acoustic images (this data path is indicated by the dashed line in FIG. 1), while other systems store the X-Y video images. The image loop stored in cine memory 16 can be reviewed via track-ball control, and a section of the image loop can be selected for hard disk storage.
For an ultrasound imaging system which has been configured with a free-hand three-dimensional imaging capability, the selected image sequence stored in cine memory 16 is transferred to the host computer 20 for three-dimensional reconstruction. The result is written back into another portion of the cine memory, from where it is sent to the display system 18 via video processor 14.
From the standpoint of the vendor of the ultrasound imaging system, it is desirable to sell or lease systems having built-in optional features which can be activated at a location remote from a central billing station. For example, the capability of free-hand three-dimensional imaging can be an optional feature which must be purchased from the system vendor. To ensure that the system user is charged for the use of such optional features, it is known to provide means for blocking activation of optional features unless authorization is obtained from the manufacturer. Authorization can also be given to allow for use of an optional feature free of charge for a predetermined trial period. In one conventional ultrasound system, this is accomplished by delivery of an authorized feature activation disk, which is inserted into a slot in the system. The disk has validation information and feature information stored thereon. The system compares the validation information with a unique validation standard pre-stored in the system memory. If the validation data matches the unique pre-stored standard, the feature information stored on the disk is incorporated in the system configuration database. Thereafter and until the expiration date, whenever the system is initialized, optional feature or features represented by the feature information of the disk will be enabled.
However, there is a need for a method of configuring an ultrasound imaging system at a remote location without physically transferring an authorization disk or card from the central location to the remote location. In particular, there is a need for a method of system configuration which can be carried out remotely while avoiding the delays inherent in the shipment or delivery of a disk or card from a central location.